Set square



P. LAGROSSE May 26, 1970 SET SQUARE Filed July 29. 1968 United States Patent O 3,513,552 SET SQUARE Pierre Lagrosse, Ave. de la Gare, Orason, France Filed July 29, 1968, Ser. No. 748,471 Claims priority, applicntion France, Aug. 31, 1967,

Inf. c1. 1i43113/00 U.S. Cl. 33-104 1 Claim ABSTRACT OF THE DISCLOSURE The invention consists of the construction of a set square the peculiarities of which make it suitable for many purposes in tracing graphs and similar work.

It features the means used taken either together or separately and in particular a surface comprising three triangles at 90, 60 and 45 respectively; the edges of the 90 angle have logarithmic graduations along one side and centimetric graduations along the other; the centre part of the set Square has a circular hole which can take a circular protractor, the centre of which is the meeting-point of the three bisectors of the angles from the three apeXes of the three triangles.

On the attached drawing, provided as a non-limiting example of one of the forms of construction of the invention, the set square is shown as a whole. l

The set square is made up of a surface formed by a 90 angle 1, a 60angle 2 and a 45 angle 3.

The edge 4 bears logarithmic graduations, while the edge 5 bears centimetric graduations.

Edges 6 and 7 have no graduations and form the profile 8 at their point of junction.

Holes 9, 10 are provided on either side of the circular centre hole 11 which enables a circular protractor to be positioned.

Around the circumference of the circle degrees 12 and grades 13 are inscribed.

The set square is equivalent to two ordinary set squares. The centre of the hole 11 is at the common meeting-point of the three bisectors 14, 15, 16 from the angles 1, 2, 3. This circular hole 11 is concentric to the inscribed circle and its radius is the length of one half side of the inscribed square in the circle itself inscribed in the instrument. v

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The quadrants are indicated by the arrows 17, 18, 19, the point of which is directed towards the centre of the hole 11.

The three bisectors 14, 15, 16 go from the apexes of the angles towards the centre hole and their perpendicular is tangential to the inscribed circle.

The advantages and uses of this new instrument are immediately evident.

The outside shape of the set square and its two holes 9, 10gives angles of 90, 60, 45, 30 and 22.5.

The bisectors 14, 15, 16 make it a centring set square. The centimetric and logarithmic graduations 4, 5 make it possibleV to trace all kinds of graphs and their coordinates.

This set square also has educational value, provided both by its shapes and by its numerical data, trigonometric and geometric functions.

However, the shapes, dimensions and layout of the various parts, as well as the materials used to make them, may vary within the limits of the equivalents without thereby changing the general concept of the invention just described.

I claim:

1. A polyvalent set square, for graphs and similar work, comprising a plane sheet-like body having yfour linear sides of which a first side and a second side include between them an angle of 90, the second side and a third side include between them an angle of and a fourth side and the rst side include between them an angle of 45 said rst side being marked with a linear scale, said second side being marked with a logarithmic scale, said body including a lirst elongated linear slot opening disposed along the bisector of the 60 angle and a second elongated linear slot opening disposed along the bisector of the 45 angle, said Ibody including a circular opening between said slot openings the centre of which is disposed at the intersection of the bisectors of the 60 and 45 angles and lines inscribed normal to the inside ends of the rst and second openings, and said body being marked about the circumference of said circular opening with degrees and graduations.

References Cited UNITED STATES PATENTS 462,126 10/1891 Griffiths 33-l04 1,667,191 4/ 1928 Chapin 33-104 FOREIGN PATENTS 342,409 7/ 1904 France. 982,896 l/1951 France.

91,801 5/ 1897 Germany. 511,868 l/1955 Italy.

HARRY N. HAROIAN, Primary Examiner 

